Algae Invasion Latest Warning For Coral Reefs

A pollution-fueled invasion of algae at one of the Florida Keys' most popular diving spots is alarming some scientists who say it shows that the Keys' colorful coral reefs are in big trouble.

During the past four months, algae that look like greenish cotton candy have wrapped themselves around corals and sea fans in portions of the Looe Key reef, one of the top diving destinations in the nation.

Meanwhile, a related alga species has blanketed parts of the reef with what looks like an underwater golf course turf, scientists say.

The discovery of the pollution-fueled cladophora algae is worrisome because the scientists fear the Keys' treasured coral reefs, which have been in severe decline, could start dying en masse from the pollution.

That would spell trouble for the Keys, where the reefs have helped make diving and fishing major attractions for the 3 million tourists who visit every year.

Finding cladophora algae on the reef is significant because the nearest island is more than three miles away, suggesting that enough pollution is flowing off the Keys that it is tainting ocean waters far from land.

Bill Matzie, a researcher at the Harbor Branch Oceanographic Institution, likens the discovery to a canary dying in a coal mine where oxygen is growing short.

Other forms of algae have been showing up increasingly on the reefs in recent years, worrying scientists.

But cladophora algae can thrive only where the waters contain high levels of nitrogen, a substance found in sewage and other waste products, said Matzie and his colleague, Brian Lapointe.

Ben Haskell, science coordinator for the Florida Keys National Marine Sanctuary, said that while he is unsure of the significance of the cladophora outbreak, the appearance of several kinds of algae on the reefs in recent years indicates something is wrong.

"We're very concerned," Haskell said.

Matzie said high levels of nitrogen are necessary for cladophora to proliferate. Absent manmade pollution, you might expect to find it close to shore where a colony of birds lives, dropping its waste into the water.

But finding enough nitrogen on a reef to support a lot of cladophora is alarming, Matzie and Lapointe say.

Where is the nitrogen coming from?

Virtually everyone familiar with the situation says that mishandling of sewage in the Keys is probably at least partly to blame.

If you believe Matzie's colleague, Lapointe, though, the cladophora discovery is even more significant. Lapointe says the nitrogen is coming from sugar cane farms 120 miles to the north, in western Palm Beach County.

Lapointe says the nitrogen is an unintended side effect of a multi-billion-dollar Everglades restoration program that has funneled lots of extra water into nearby Florida Bay in recent years.

Sewage and other pollution from the Keys are significant, Lapointe says, unleashing 700 tons of nitrogen each year. In 1992, he documented how a big rainfall washes nitrogen and phosphorus out to the Looe Key reef.

But Lapointe thinks nitrogen-rich water flowing out of the Everglades is an even more important factor. More than four times as much nitrogen pours into Florida Bay than is unleashed by Keys sewage, he says, and even though that source is 50 miles from the Looe Key reef, it's a big cause of the problems.

Other scientists familiar with the situation dispute that notion.

It's true that water flowing off the sugar fields is extremely high in nitrogen, said Ron Jones of Florida International University.

But the northern Everglades in Broward and Palm Beach counties acts as a kind of filter, Jones says, cleansing the water of nitrogen. Once the water reaches the mangroves of the southern Everglades, it picks up more nitrogen from decomposing leaves and other plant material.

But that's natural, Jones said, and has been going on for thousands of years.

While Lapointe and Matzie consider the cladophora discovery a threshhold of sorts - a signpost proclaiming the situation really bad - it is only the latest in a line of trouble signs:

-- Lapointe's measurements show that nitrogen levels in the Keys are two to three times as high as corals - which are actually millions and millions of tiny invertebrate animals - can stand.

-- University of Georgia researchers documented a loss in coral at Looe Key of more than 40 percent from 1984 to 1989 .

-- Several highly visible diseases that produce white lines, bleaching and black bands on the Keys' corals, all signs of disease that eventually kills the animals that make up the reef, have been noted in recent years.

Bill Kruczynski, a scientist with the U.S. Environmental Protection Agency, is overseeing some of Lapointe's research. He and other scientists say that even if something other than sewage is contributing to the problems, the sewage is definitely a factor.

An estimate by the marine sanctuary put the price tag for controlling Keys sewage at $275 million to $495 million.

The appearance of cladophora algae, while alarming to the trained eyes of Lapointe and Mitzie, has gone largely unnoticed by divers.

Said dive boat captain Ed Lotkowictz, who is based at Little Torch Key: "I don't see that it is affecting business. If anything, the popularity of Looe Key is increasing all the time."

Wait long enough, warn Lapointe and other scientists, and the damage will be much more obvious.